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True/False: The styloid process of the ulna extends more distally then the styloid process of radius
False; Styloid process of radius extends more distally
Serves as a pulley for EPL, ECRB, ED, IE tendons
Dorsal tubercle of Radius / Lister’s Tubercle
Angulations of the distal radius
Ulnar Tilt - 23 deg towards Ulna
Palmar / Volar Tilt - 11 degrees toward palm
Normal ulnar tilt of the distal radius
23 degrees towards the ulna
Normal volar tilt of the distal radius
11 degrees towards the palm
AKA navicular bone
Scaphoid
How many carpal bones does scaphoid come to contact with?
four carpal bones
Most commonly fractured carpal bone
Scaphoid
MOI of Scaphoid fracture
Wrist extended and radially deviated
The Scaphoid and lunate receives _____ of axial load
80% of axial load
True/False: the scaphoid is most mobile during abduction/adduction
False; Most mobile during flexion/extension
Most frequently dislocated carpal bone
Lunate
True/False: The lunate has least motion during flexion-extension
True
AKA triangular carpal bone
triquetrum
The only carpal bone with one articulating surface
Pisiform
What muscle attaches to the pisiform?
Flexor Carpi Ulnaris
AKA Greater Multangular
Trapezium
Trapezium and scaphoid forms the _____ of anatomic snuffbox
floor
AKA less multangular
Trapezoid
AKA Os Magnum
Capitate
Largest carpal bone
Capitate
True/False: The Scaphoid is the Axis of all wrist motion
False: Capitate
Keystone of the Wrist
Capitate
Articulating Surfaces for Radiocarpal joint
PROXIMALLY: biconcave distal end of the radius and the radioulnar articular disc (part of triangular fibrocartilage complex; TFCC)
DISTALLY: biconvex scaphoid, lunate and triquetrum
Articulating surfaces for Mid Carpal Joint
Between the proximal and distal row
SCAPHOID TO TRAPEZIUM, TRAPEZOID, CAPITATE
LUNATE TO CAPITATE
TRIQUETRIUM TO HAMATE
What type of joint is the Radiocarpal joint
Synovial biaxial ellipsoid joint
What type of joint is the Transverse carpal joint
Synovial planar joint
Movements in the Radiocarpal joint
Volar flexion → Hyperextension
Radial (abduction) → ulnar (adduction) deviation
Movements in the Transverse Carpal joint
Gliding
Planes + Axis of Radiocarpal joint
Sagittal Plane - X axis
Frontal plane - Z axis
Planes + Axis of Midcarpal joint
None; Gliding movements
OPP of radiocarpal joint
Neutral, slight ulnar deviation
OPP of Midcarpal joint
Neutral, slight flexion and ulnar deviation
CPP of radiocarpal joint
Full extension, radial deviation
CPP of transverse carpal joint
Full extension
Radiocarpal Wrist flexion ROM
50 degrees
Radiocarpal Wrist extension ROM
35 degrees
Radiocarpal ulnar deviation ROM
2/3 of the motion
Radiocarpal Radial deviation
½ of the motion
Midcarpal Wrist Flexion ROM
35 degrees
Midcarpal joint wrist extension ROM
50 degrees
Midcarpal ulnar deviation ROM
1/3 of the motion
Midcarpal radial deviation ROM
½ of the motion
Arthrokinematics of Radiocarpal Joint
Opposite Roll and Glide
Arthrokinematics of Midcarpal joint
Opposite Roll and Glide
How many DoF does the midcarpal joint have
2; contributes to flex-ext & abd-add
Primary Muscles of Wrist Extension
extensor carpi radialis longus
extensor carpi radialis brevis
extensor carpi ulnaris
Secondary Muscles of Wrist Extension
Extensor Digitorum
Extensor indicis
Extensor digiti minimi
Extensor pollicis longus
At 90 deg, this muscle can flex elbow if biceps and brachialis are paralyzed
Extensor carpi radialis longus
This muscle only acts as a wrist extensor only when the digits are simultaneously extended
Extensor Digitorum
Primary Movers of Wrist Flexion
Flexor carpi radialis
Flexor Carpi ulnaris
Secondary Wrist Flexors
Palmaris longus
Flexor digitorum profundus
Flexor digitorum superficialis
Flexor Pollicis Longus
Abductor pollicis longus
Wrist Ulnar Deviators
Extensor carpi ulnaris
Flexor Carpi ulnaris
Primary Radial deviators
Extensor carpi radialis longus
Flexor Carpi ulnaris
Secondary Radial Deviators
Secondary (Houglum & Bertoti, 2012)
extensor pollicis brevis
abductor pollicis longus
Secondary (Levangie et al., 2019)
extensor indicis
flexor carpi radialis
flexor pollicis longus
Most important for wrist stability
Tension of ligaments
No muscles inserts on carpal except for ___________
flexor carpi ulnaris
Most Radial Deviation occurs at what joint? Why?
midcarpal joint; RD at RC at is limited as the radial side of the carpal impinge against the styloid process of the radius
Main function of the wrist extensors
Position and stabilize the wrist for activities involving the fingers
Most active wrist extensor during light closure
ECRB
Grip strength is reduced when the wrist is fully flexed because of 2 factors:
Finger extension is in passive insufficiency
Finger flexion is in active insufficiency
Order of muscle activation as grip force increases
ECU - ECRL - ECRB
At >15 elbow flexion, wrist extensor perform what action?
Elbow flexion